Method for recovering chloromethyl methyl ether

Abstract

In a reaction for introducing chloromethyl groups into an aromatic crosslinked copolymer by reacting chloromethyl methyl ether to the aromatic crosslinked copolymer in the presence of a chloromethylation reaction catalyst, a method for recovering chloromethyl methyl ether from the reaction mixture, which comprises the following steps 1) a step of adding to the reaction mixture an aqueous acid solution which is capable of dissolving the chloromethylation reaction catalyst without decomposing chloromethyl methyl ether, and an extraction solvent which is inert to and miscible with chloromethyl methyl ether and which is capable of swelling the chloromethylated aromatic crosslinked copolymer, 2) a step of contacting hydrogen chloride gas to the reaction mixture and the extract solution from the step 1 to convert decomposition products of chloromethyl methyl ether, to chloromethyl methyl ether, 3) a step of separating the resulting mixture from the step 2 into an extraction solvent layer containing chloromethyl methyl ether and an acid-containing aqueous layer, and 4) a step of separating the chloromethyl methyl ether from the extraction solvent layer separated in the step 3.

What is claimed is: 
     
       1. In a reaction for introducing chloromethyl groups into an aromatic crosslinked copolymer by reacting chloromethyl methyl ether to the aromatic crosslinked copolymer in the presence of a chloromethylation reaction catalyst, a method for recovering chloromethyl methyl ether from the reaction mixture, which comprises the following steps: 1) a step of adding to the reaction mixture an aqueous acid solution which is capable of dissolving the chloromethylation reaction catalyst without decomposing chloromethyl methyl ether, and an extraction solvent which is inert to and miscible with chloromethyl methyl ether and which is capable of swelling the chloromethylated aromatic crosslinked copolymer,   2) a step of contacting hydrogen chloride gas to the reaction mixture and the extract solution from the step 1 to convert decomposition products of chloromethyl methyl ether, to chloromethyl methyl ether,   3) a step of separating the resulting mixture from the step 2 into an extraction solvent layer containing chloromethyl methyl ether and an acid-containing aqueous layer, and   4) a step of separating the chloromethyl methyl ether from the extraction solvent layer separated in the step 3.   
     
     
       2. The method for recovering chloromethyl methyl ether according to claim 1, wherein the aromatic crosslinked polymer is a styrene-divinylbenzene crosslinked copolymer. 
     
     
       3. The method for recovering chloromethyl methyl ether according to claim 1, wherein the chloromethylation reaction catalyst is a Lewis acid. 
     
     
       4. The method for recovering chloromethyl methyl ether according to claim 1 or 3, wherein the aqueous acid solution which is capable of dissolving the chloromethylation reaction catalyst without decomposing chloromethyl methyl ether, is an aqueous hydrochloric acid solution having a concentration of at least 30 wt %, or an aqueous sulfuric acid solution having a concentration of from 40 to 70 wt %. 
     
     
       5. The method for recovering chloromethyl methyl ether according to claim 1 or 4, wherein the aqueous acid solution which is capable of dissolving the chloromethylation reaction catalyst without decomposing chloromethyl methyl ether, is added in an amount of from 100 to 1,000 wt % relative to the amount of the chloromethylation reaction catalyst. 
     
     
       6. The method for recovering chloromethyl methyl ether according to claim 1, wherein the solvent which is inert to chloromethyl methyl ether and which is capable of swelling the chloromethylated aromatic crosslinked copolymer, is selected from the group consisting of aromatic hydrocarbons and halogenated hydrocarbons. 
     
     
       7. The method for recovering chloromethyl methyl ether according to claim 1 or 6, wherein the solvent which is inert to chloromethyl methyl ether and which is capable of swelling the chloromethylated aromatic crosslinked copolymer, is added in an amount of from 100 to 2,000 wt % relative to the amount of the chloromethylated aromatic crosslinked copolymer. 
     
     
       8. The method for recovering chloromethyl methyl ether according to claim 1, wherein after adding the aqueous acid solution, the extraction solvent is added. 
     
     
       9. The method for recovering chloromethyl methyl ether according to claim 1 or 8, wherein the step 1 is carried out at a temperature of at most 50° C. 
     
     
       10. The method for recovering chloromethyl methyl ether according to claim 1, wherein each of the steps 1, 2 and 3 is carried out at a temperature of at most 50° C.